Most of the e-collar trainers out there do what doberkim said, they use the collar for absolutely EVERYTHING.
They put a shock in place of verbal corrections, leash correction and verbal guidance.
Before I even put the collar on, after speaking with some of the best in e-collar training, or the best as other e-collar people label them, I had already drilled into my OWN head, that I wouldn't be using the collar the same way they instructed me too. I made MY OWN limits for the collar, based on me, my dog and in general, my own personal opinion on what was neccessary.
So many people get talked into using the collar where it's not neccessary and over use of the collar where it's not neccessary.
I have my collar, I haven't used it that much, but it was a difficult choice that was made based on the fact that I had, in my opinion, and other respectable trainers opinions, exhausted every other method to the best of my ability.
As BB said, for walking off leash, IMO, I don't really feel an e-collar is neccessary.